1. Field of the Invention
The present invention relates to a method of displaying maps for a car navigation unit, and particularly a method in which the entire display screen can be employed for displaying one map (one-screen map display), or the display screen can be divided into two parts for simultaneously displaying both a wide area map and a detailed map on each of the divided screens (two-screen map display).
2. Description of the Related Art
In the conventional car navigation unit, to give a driver of a vehicle route guide information whereby the driver can easily arrive at a desired destination, the following operations are performed: detecting the position of the vehicle, reading out map data surrounding the vehicle position from the CD-ROM, displaying a map image on the display screen, superposing the vehicle position mark at a specific position on the map image; and moving the vehicle position mark on the display as the vehicle moves to change the present position, or scrolling the map image while fixing the vehicle position mark at a specific position on the center of the display screen. As a result, the driver can get ostensibly understandable map information surrounding the vehicle position.
However, the conventional car navigation unit is designed to present only one map on the display screen. Therefore, when presenting a detailed map (expanded map) on the display screen, the driver may not find where the position indicated by the vehicle position mark is. And, when presenting a wide area map (reduced map), the driver cannot find the precise position of the vehicle. Accordingly, the driver usually displays the wide area map and the detailed map alternately on the screen to thereby recognize the vehicle position. However, this method requires frequent switching operations between the wide area map and the detailed map, which imposes a danger to safe driving as well as gives poor operability to the driver.
The present invention has been made in view of the foregoing problems, and an object of the present invention is to provide a method of displaying a wide area map and a detailed map simultaneously on the display screen, and scrolling the detailed map on a cursor screen synchronously with a cursor movement on the wide area map, whereby the driver can easily comprehend the vehicle position on the map.